Many cores however come from regions where the yearly snowfall accumulation is too small for the annual layers to be distinguished, and other methods of dating must be used.
Although Lamont Geological Observatory was not established until 1949, the earliest cores in the Repository collection were taken in 1947, on the R. ATLANTIS, by Maurice Ewing, Lamont’s founder and first director. Scientists from all over the world have studied samples from the Repository’s vast number of cores and, in the last decade, use of the material has increased dramatically in direct response to increased interest in studying past climate.
Ewing believed that if Lamont gathered as many cores as possible, from as many places as possible, patterns would emerge that would reveal the geological history of our planet. The Repository now includes 18,700 cores from 11,500 sites in all the major ocean basins, including the Arctic, as well as from many of the marginal seas.
This flow-thinning means that annual layer counting eventually becomes impossible in all deep cores.
Where layer-counting is not possible, dating generally relies upon mathematical models of ice flow.
They allow us to go back in time and to sample accumulation, air temperature and air chemistry from another time.